A internal WD 320 GB Scorpio Black would be my recommendation. 7200 rpm so you get a nice boost. i like the western digital My Books, i have 4. 2 500's & 2 1TB. the usb only drives are cheap and used for storage. the usb, firewire 800, sata combos are my workhorses, they cost more but i use them every day. i do a lot of limewire, like 24/7 i have a couple of WD TVs http://www.wdc.com/en/products/index.asp?cat=30
i play my movies and music on my tv's with them